ArduCopter 2.9 / 2.9.1 released

ACRO bug (fixed in 2.9.1b): while doing flips in ACRO mode, if you switch to Stabilize while inverted your throttle will go to minimum. To regain throttle control you need to switch back to ACRO then back to Stabilize again (i.e. switch to stabilize twice). You never lose control of roll/pitch/yaw.

Loiter/AltHold/Auto/RTL bug: if you switch into these modes with throttle at zero motors will go to minimum until you raise the throttle.

Auto mode altitude bug (fixed in 2.9.1b): setting a waypoint altitude greater than 320m over home altitude may wrap around and instead be interpreted as a low altitude.

Landing improvements (Leonard/Randy). Copter will descend to 10m or until an object is sensed with the sonar. Then slows to 50cm/s descent (speed can be adjusted with LAND_SPEED parameter). (video).

Surface tracking with sonar (Randy/Leonard). Copter will attempt to maintain current distance from objects in front of sonar regardless of altitude. Only used in alt-hold and loiter, not used for missions. Sonar can be enabled/disabled with CH7 switch. (video)

As per usual PIDs are optimised for the 3DR/jDrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

Special thanks to our testing team lead Marco and the dedicated bunch on the 2.8.1 release thread who put their copters at risk while testing the pre-release version. Some of their videos are here: 12345678

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

Replies to This Discussion

By the way, if after doing the accel calibration and adding the vibration dampening foam you still can't get good performance please try:

If using APM2.x change the AHRS_MPU6K_FILTER to 20

Verify that vibration isn't your problem by enabling the "RAW" message through the cli, do a quick flight in stabilize mode and check the Accel Z values. If they move around too much you've got a vibration problem so you might want to check other possible sources including props and motors. Here is an example of good and bad values.

Excellent job! However have run into to a problem where directly after loading 2.9 I can't connect at all using the same port and baud that I loaded the firmware with? No heartbeats received. Tried twice. Will do a full erase now to see if that helps...

EDIT: had to unplug the flight battery and replug the USB and now connection is confirmed, off to setup and test...

- Alt Hold is very, very good, if anything a tiny bit busy but that's just nitpicking.

- Loiter is VERY busy/fidgety as it was in v2.8.1, I haven't yet upgraded my onboard mediatek GPS, will this help with this fidgetiness? How else to stop or lessen this? It makes trying to take an onboard video in Loiter really bad.

Ah, yes. I was a little vague on the throttle rate and altitude gains. If you look closely at the image just below those comments you can see the defaults:

Altitude Hold P: 2.0 I:0

Throttle Rate P: 6.0 I:0 D: 0.2

Generally we think people should go with these and adjust the Throttle Accel P and I values to suit their frames.

We highly recommend upgrading the mediatek firmware to 1.9. It brings the mediatek much closer to the performance of the ublox. Still, the default Loiter Rate P is a bit high, better to start with 2.4 and move it up until it gets too busy.

By the way, loiter and navigation will be reworked in 2.9.1 and we expect it'll get much less busy and when move around in loiter it will have a much more natural feel (video).

Default value for AHRS_GPS_GAIN is 1.0 for 2.9 release. In the 2.8.1 release thread, some advise to lower this gain to 0 for 2.9-RCx. So, is it still necessary to lower this gain, for Mediatek user or Ublox user ?